The U.S. Constitution gives the power to impose taxes — including tariffs — to Congress. But lawmakers have gradually relinquished power over trade policy to the White House. And Trump has made the most of the power vacuum, raising the average U.S. tariff to more than 18%, highest since 1934, according to the Budget Lab at Yale University.

President Donald Trump has succeeded in strong-arming nations to accept higher tariffs on US exports, yet for now experts see little threat to the postwar trend of lower duties in the pursuit of greater wealth all around.